Mom trying to change my child's name

Okay I know she can't do it. But my mom has not shut up about changing what I'm naming my baby boy. I'm 20 weeks today and she still tries making suggestions even though I've already decided on a name long ago. Me and my ex chose Jeremiah Ethan when we were dating 3 years ago. Well my cousin had a baby about 1.5 years ago and decided to name the child Ethan. Now my mom insists that I change mine even though I picked it out long before I knew about my cousins decision on naming his child Ethan and 2 even though we're not even gonna call him Ethan he will be Jet to us and in school and such it will be jeremiah. What can I do so I don't hurt her feelings....I mean over told her a million times but she just won't drop it???